Devices of various designs have been known for rotary entrainment of an associated means, e.g. a lock follower or a window drive, which entrainment may be suppressed if need be.
For example, DE-U-8 624 544 provides for mounting on a frame, an installation body to which the handle is axially fast connected and which includes engaging means that define preferred or standard angular positions of the handle. EP-B-0 386 651 and EP-B-0 460 297, too, describe each a lockable window handle with a jaw-coupling locking mechanism acting in two steps, whereby the window can be swung open only if the handle has been unlocked. With this arrangement, the window may be tilted even with the handle locked so that the room can always be aired, in fact also by operators who do not have keys.
Some window handles are provided with a push-button unit as an axially movable safety element by means of which, however, even unauthorized persons can bring about or change the closed condition merely through pressing or releasing the push-button. That is undesirable or even inadmissible for certain applications.
DE-U-299 13 559 describes a handle that may optionally be used with or without locking device. It may be equipped—in particular on site—with a cylinder which may be removed at any time, e.g. for replacement by a different locking system. For this purpose, the handle neck has a recess into which a lock cylinder suitable for a key master system may be fitted that acts on an interlocking ring via an adapter designed to be rigidly mounted at the lower end of the cylinder. However, only two final positions of the lock cylinder can be selected.